1. Field of the Invention
This invention related to an inverter-integrated electrical rotating machine.
2. Description of the Related Art
Conventionally, a inverter-integrated vehicle electrical rotating machine has been proposed in which reduction in size and weight and reduction in wiring loss are realized by integrating an inverter with a polyphase AC electrical rotating machine, the inverter being provided between a DC power source and an armature wiring of the polyphase AC electrical rotating machine to enable supply and reception of power, and the inverter applying a polyphase AC voltage to the armature wiring.
This inverter needs to be protected electrically and mechanically since it is a circuit device in which many power transistors (switching devices) and an inverter control circuit for performing driving control of the power transistors are wired in a complicated manner. Therefore, in the conventional inverter-integrated vehicle electrical rotating machine, the inverter is sealed in a closed box or case made of metal or resin and fixed on a circumferential wall or end wall of the housing of the electrical rotating machine. Hereinafter, the mode of fixing the inverter on the circumferential wall is called circumferential wall fixing mode, and the mode of fixing the inverter on the end wall is called end wall fixing mode.
However, the switching devices of the inverter generate large power loss at the time of switching and making electrical continuation in electrically driving the electrical rotating machine. Therefore, it is a particularly important task to cool each switching device constituting the inverter. Conventionally, an air cooling mode of cooling the inverter by cooling air and a water cooling mode of cooling the inverter by cooing water have been known.
For example, in the air-cooling end wall fixing mode disclosed in JP-A-7-231672, an inverter having a rotary shaft formed in a U-shape or horseshoe-shape on a radial cross section is used. This inverter of the air-cooling end wall fixing mode is advantageous for realizing reduction in constitution and reduction in size and weight since reduction in motor diameter and simplification of the cooling mechanism can be expected. This inverter is particularly preferred when it is provided in a field-coil-type synchronous motor because the inverter can be arranged at a position that overlaps the position of the brush in the axial direction and that is different from the position of the brush in the circumferential direction.
However, in the above-described inverter-integrated vehicle electrical rotating machine of the air-cooling end wall fixing mode, it is not easy to highly protect each switching device of the inverter electrically and mechanically, maintain sufficient cooling of each switching device, and realize miniaturization of the inverter at the same time.
On the other hand, as disclosed in JP-A-2004-274992, a technique of inverter-integrated vehicle electrical rotating machine has been proposed in which good electrical and mechanical protection of the switching devices of the inverter, high switching device cooling performance and miniaturization of the inverter are realized at the same time.
However, in the inverter-integrated vehicle electrical rotating machine of the air-cooling end wall fixing mode disclosed in JP-A-2004-274992, it is difficult to realize further improvement in cooling while highly protecting each switching device of the inverter electrically and mechanically.
More specifically, in order to provide good electrical and mechanical protection of the switching devices of the inverter and the power wiring and control wiring for connecting the switching devices, these elements must be sufficiently sealed and fixed in the case with insulating resin or the like. However, if the sealing property is thus improved by using insulating resin or the like and the case is miniaturized, the surface area of a cooling heat sink part is significantly reduced and the construction of a cooling air passage becomes inappropriate. This causes a problem that the cooling property of the switching devices or the like is deteriorated.